The present invention relates generally to slicing of apples. The present invention is designed to automatically slice apples into wedges for use in packaged fruit salads sold in restaurants or in packaged sliced fruit sold, for example, in supermarkets. More particularly, the present invention relates to an apparatus for optimizing the slicing of apples which results in minimum cell damage to the apple which, in turn, extends the shelf-life of packaged apple slices.
The demand for packaged fruit salads or packaged fresh sliced apples has grown dramatically. Consumers having less time available for preparing meals and greater concern for eating fresh fruit have increased the demand for packaged fruit salads. The single largest problem in selling packaged, sliced apples is that the apple slices turn brown over time and become unacceptable to consumers.
The browning of freshly cut apples is caused by oxidation of one or more enzymes released from apple cells that are cut open or ruptured during the slicing operation. The enzymes are liquid and tend to spread across the freshly cut apple surface. As those enzymes oxidize, they turn brown. This oxidation process is described in detail in U.S. Pat. No. 6,054,160 at column 1, line 13 through column 3, line 16, incorporated herein by reference.
The prior art includes various attempts to delay or prevent the browning of sliced apples.
For example, the prior art includes a variety of liquids that are applied to sliced apples in an attempt to neutralize the enzymes or to otherwise delay the onset of browning (see U.S. Pat. Nos. 5,922,382; 5,914,143; 5,939,117; 5,922,382 and 6,054,160. The primary disadvantage of this approach is that the apple slices tend to absorb the applied liquid (which is usually applied in the form of a bath or spray) and become “waterlogged,” losing their crispness and desirability, thereby becoming unacceptable to consumers.
The prior art also includes the use of transparent plastic covers for packaged salads or apple slices to reduce the amount of oxygen in the ambient air that reaches the sliced apple surfaces (see U.S. Pat. Nos. 5,922,382 and 6,054,160). This technique covers the entire packaged salad (rather than sealing each cut surface), allowing ambient oxygen inside the package to react with the freshly cut apple surfaces. Furthermore, such transparent covers are relatively expensive and not totally impermeable to air and allow oxygen and air to pass through over time.
In fact, the prior art includes several genetically engineered species of apple tree wherein the apples have a delayed onset of browning after being sliced (see U.S. plant patents 4,956; 7,857; 13,930 and U.S. 2006/0053517P1). The difficulty with a genetically engineered apple is that the taste does not satisfy the large majority of consumers who favor the taste of known varietals such as Fuji, Granny Smith, Delicious and a host of others.
The prior art includes U.S. Pat. No. 4,007,676, owned by the assignee of the present application. The '676 patent teaches an apple slicer for cutting wedge shaped apple slices. The blades have a thickness of about 0.020 inch (or 500 microns) and are tensioned by a pair of screws (see column 9, lines 48-69). Applicants have found that simply tensioning the blade with the tensioning screws of the '676 patent is inadequate when using blades thinner than 500 microns.
The problem addressed by the present invention is how known varieties of apples can be sliced and packaged in a manner to delay the onset of browning while preserving crispness and taste.
The present invention significantly delays the onset of browning while preserving crispness and taste. A key aspect of the present invention is the use of a significantly thinner blade than heretofore used in automatic apple slicing machines. The thinner blade must be used together with a novel system for supporting and tensioning the blade to resist bending, warping and twisting as described below. The thickness of the blade utilized in the present invention is roughly equivalent to the diameter of most apple cells, i.e., less than 300 microns and preferably about 200 microns. As shown in FIG. 27, typical apple cells are roughly 250-300 microns in width. FIG. 27 is a reproduction of FIG. 1 from a paper entitled “Cell Boundary Detection and Volume Approximation of Confocal Microscope Images for Quantitative Analysis of Osmotically Dehydrated Plant Tissues” available at http://www.kremer.ca/Publications or http://www.kremer.ca/Publications/Papers/Applespiderpaper.pdf.gz The significance of FIG. 27 is that it illustrates that the present invention has reduced the blade thickness by roughly the width of a typical apple cell. A reduction of such magnitude will inherently reduce the amount of apple cell damage caused by the slicing operation. Applicants are not aware of prior art apple slicing blades having a thickness less than about 500 microns. As shown and described below, the use of a 200 micron thick blade cuts or ruptures less than half the cells that are cut or ruptured by a prior art blade of 500 micron thickness. The swath or kerf of the thinner blade is less than half that of a 500 micron thick blade. The reduction of the number of cut or ruptured apple cells inherently delays the onset of browning by reducing the amount of oxidizable enzymes released by cut or ruptured cells. The reduced volume of oxidizable enzymes is neutralized by known agents applied in much lower quantities than utilized in prior art apple slicers, thereby avoiding “waterlogged” apple slices while preserving crispness and a fresh appearance. Additionally, significant cost savings are realized by the use of a smaller volume of sealant and/or neutralizing agents.
We have found that the use of a significantly thinner blade than used in the prior art automatic apple slicers requires the use of a novel and robust clinch buckle support for the outer end or ends of each blade, along with adjustable blade tensioning, described below in detail. The supporting and tensioning of each blade prevents the blade from twisting, bending or warping as the slicing is done. It is critical to avoid twisting, bending or warping of the blade, since those movements of the blade greatly increase cell damage and usually result in apple slices with distorted and unacceptably cut surfaces.
A first embodiment of the present invention utilizes a plurality of generally V-shaped blades having bent tabs at the outer ends or tips of the legs of each blade, wherein each blade is independently supported and tensioned. The apex (or “inner end”) of each V-shaped blade is supported by a central hub; the bent tabs formed at the two outer ends of the blade are rigidly connected to and supported by a clinch buckle to stiffen the blade. Furthermore, each clinch buckle is preferably “captured” between two surfaces of the outer blade support ring to prevent rotation of the clinch buckles, thereby further stiffening the blades. An adjustable tensioning device is used to move or draw the clinch buckle radially outwardly and away from the inner hub or blade apex toward the outer blade support ring
In a second embodiment, a plurality of single blades extends between a central or inner hub and a cylindrical outer blade support ring. Both ends of the blade are firmly and rigidly supported. The outer ends of each blade are connected to a clinch buckle as briefly noted above, and each clinch buckle is in turn adjustably mounted to the outer blade support ring for blade tensioning. Each blade is separately and independently tensioned from the exterior of the outer blade support ring.
A primary object is to provide an apparatus for automatically slicing apples which minimizes apple cell damage and delays the onset of browning, while preserving crispness and taste.
A further object is to provide an apparatus for automatically slicing apples wherein a significantly thinner blade is used as compared with prior art apple slicers, and wherein the thinner blade is supported and tensioned to minimize and/or eliminate bending of the blade and to minimize apple cell damage.
Other objects and advantages of the invention will become apparent from the following description and drawings wherein: